I, The Celestial Dragon, Rule The Heavens Through The Double Gate - Chapter 12: Be My Blade.

The little handsome son-in-law passed through a world as waste material and the husband of a wealthy family. But because of his lacking aptitude, the wealthy family had driven him out. So he worked hard and found a more powerful family’s thighs to hold onto. Soon enough, he became the strongest son-in-law and husband in history.

In this world, it was impossible to practice martial arts. It was futile so he might as well take advantage of his wife’s thighs and maintain a comfortable and leisure lifestyle.

He’ll train his wife to become the strongest and best person in the world.

“Whoever dares to provoke me, let my wife kill you!”

- Description from Novelupdates

Synopsis below:How did the Avatar universe change when a transmigrant appeared in an unknown village, long before the canonical events? And how are the two islands Kyoshi Island and Uzushiogakure no Sato (A village hidden in the maelstrom)?---Tags: AU, Before-canon, Post-canon, Violence, Death of major characters, Transmigration, Harem, Children, Incest, Romantic. Foul language.

The figure of the Armada seems to be still riding the wind and waves in the Atlantic Ocean, and the gold of South America still seems to flow in continuously. As Alfonso from the Bourbon family returns to the Royal Palace of Madrid where he was born, the story begins here…

- Description from novelbuddy

Qin Chen crossed into Taiyi Holy Land as a sweeper, and at the age of sixteen awakened the system. As long as he signed in at different places, he could get different rewards.

Sign in at the Land of Emperor Ruins and get the world’s No. 1 Chaos Holy Body and the Chaos Emperor Sutra!

Sign in to seal the magic land and get the quasi-emperor soldiers!

Sign in at the Refining Hall and get the God-level Refining Technique!

Sign in at the medicine garden and get the medicine of immortality!

Sign in at the Imperial Palace and get the Emperor-level forbidden magical power ‘Resurrection from the Dead’!

…

Qin Chen thought that he would just sign in silently until the world was invincible.

One day, the relics of the Great Emperor will appear in the Holy Land, all the holy places, families, and ancient dynasties have come, and there will be an unparalleled demon king in the relics, killing countless powerhouses, ruling the world, and wanting to destroy the Holy Land.

In desperation, Qin Chen could only walk out, slapped the Demon King to death, and sighed: “I just want to be a sweeper and sign in silently. Why do you force me to take action?”

- Description from novelbuddy